Calculating device



July 18, 1950 L. M. NATlON-TELLERY -Louis Miles Ncni eeeeeeeee y AAAA ts y 1950 M. NATION-.TELLERY 2,515,739

CALCULATING DEVICE Filed July 30, 1947 8 Sheets-Sheet 3 Fig. 3. Z? 22 2523 25 24 23 1F III ' WWW-W L. M. NATlON-TELLERY 2,515,789

CALCULATING DEVICE July 18, 1950 Filed July 30, 1947 8 Sheets-Sheet 4 tar/mg y 1950 M. NATlON-TELLERY 2,515,789

CALCULATING DEVICE Filed July 30, 1947 8 Sheets-Sheet 5 ig 7A.

y 8, 1950 L. M. NATlON-TELLERY 2,515,789

' CALCULATING DEVICE Filed July 30, 1947 8 Sheets-Sheet 6 Fig. F5.

U9876S432IO July 18, 1950 L. M. NATlON-TELLERY CALCULATING DEVICE 8 Sheets-Sheet 7 Filed July 30, 1947 2 I 3 II!!! 222/! 0 33222]! 0 44 3322]! 0 5 4 7 5 III I Il 3533322222 5554443333 7766655444 9988776655 8 7 0 9 2222222222 5555544444 8887776666 l0@@@99888 443322 0 0 5 3 33 3333 7777766666 000@@@9993 55 4 3222 99098776655 4 3 9 7 4444 444444 9939988888 444333222 9988877 66 445522 00 7 6 3 5555555555 OOO O 7776665555 33222 000 9988776655 9 7 5 6666666666 3333322222 @@@mw998888 7766655444 443322 /00 3 2 9 777777777 5555544444 333222I/l/ G9S868 8 877 6655 6 5 5 3 Y 8888888888 7777766 66 666 554444 5 4433222 .443322 0O 9 oo 9 7 Fig! 8A.

Patented July 18, 1950 UNITED STATES PATENT OFFICE CALCULATING DEVICE Application July 30, 1947, Serial No. 764,741 In Great Britain April 13, 1945 Section 1, Public Law 690, August 8, 1946 Patent expires April 13, 1965 15 Claims. 1

This invention relates to a calculating device which can be quickly adjusted to set up a multiplicand or divisor having any number of digits up to a maximum number provided for in the device, and which gives a direct and immediate indication of a product or quotient when the multiplier or quotient is a single digit, multipliers or quotients of more than one digit being dealt with by the method of successive multiplication of single digits or successive division of remainders.

For convenience, the invention will hereinafter chiefl be described with reference to a calculating device for performing multiplication, but it is to be understood that it is also applicable to devices for performing division and the references to multiplication in the following specification and the appended claims are to be read in this sense.

According to this invention a device is provided which comprises a plurality of rotatable elements each having associated therewith a plurality of figures, means co-operating with each of said rotatable elements for exposing selected figures of said elements, and means for automatically transmitting the movement of each of said rotatable elements to the figure-exposing means associated with the next adjacent rotatable element for adjusting the figure selected from this element for exposure.

Regarded from another aspect the invention comprises a plurality of rotatable elements each carrying a plurality of figures, means for exposing rows of figures selected from said rotatable elements and representing successive products of an arbitrary factor, and means for controlling the selective exposure of figures in joint dependence on the setting of the rotatable element carrying this figure and the setting of the next preceding rotatable element.

Preferably the device is provided with nine rows of digits, and the arrangement is such that the setting up of a desired multiplicand along a separate key row of figures in the device automatically sets up these nine rows of digits respectively representing the products of 1 to 9 times this multiplicand. Thus, to obtain the product of this multiplicand and a multidenominational multiplier, it is only required to add appropriatel the partial products shown. It will be apparent therefore, that the device according to the invention can be used to obtain any product of a multiplicand having any number of digits up to a maximum determined by the number of columns provided in the device.

Each of the figures shown when a multiplicand is set up on the device is advantageously arranged to be automatically selected from a predetermined table and is exposed through a window provided in a panel of the device associated with the particular table, the remaining figures of the table in question being kept hidden or masked.

In an important feature of the invention, to provide for th carry-over of numbers from one denomination to the next higher denomination, each table provides for a denomination higher than the first bears a set of vertically-spaced rows of horizontal digits and means is provided for selecting, in dependence on the setting of the column corresponding to the next lower denomination, that row of the table from which a digit is to be exposed, the entries in these rows of horizontal digits taking into account the number to be carried over from the previous denomination.

According to another feature of the invention, provision is also made for carrying over numbers from one denomination to the second-higher denomination by providing appropriate tables with additional entries which result from this carryover, and by providing the corresponding and exposed digit of the first higher denomination column with a characteristic marking for signalling to the user of the apparatus that the additional entry in the next higher column must be selected.

In this way the necessity for mentally adding integers which have to be carried over to higher denominations is completely avoided.

The various sets of digits may be printed or otherwise marked on a plurality of endless bands or, as in the specific example to be described, on a plurality of rollers, and the arrangement is such that only one column of digits is available for viewing at one time.

In order that the invention may be fully understood and readily carried into effect, one embodiment thereof, given by way of example, will now be described with reference to the accompanying drawings. In these drawings,

Figure 1 is a perspective view of a complete calculating device according to the invention, having its parts in a position in which it is set to show a series of products of an arbitrarilyselected factor.

Figure 2 is a plan View of the indicating surface of the device shown in Fig. 1.

Figure 3 is a plan view of three of the rollers used in the device.

Figure 4 is a side view corresponding to Fig.

Figure 5 is a plan view of a detail of the indicating surface.

Figure 6 is a section on 66 of Fig. 5.

Figures7A and'lB illustrate the surface of the roller corresponding tothe units column of the device, this surface being shown developed on to a plane.

Figures 8A and 8B illustrate the development I of the surface of one of the remaining rollers on to a plane.

The calculating device illustrated in the drawings comprises a casing generally denoted I having a top or indicating surface 2"which. is inclined to the horizontal to facilitate reading the figures appearing thereat.

The top surface 2 is divided up by a seriesof.

cross strips 3, running vertically and horizontally, into a plurality of separate panels 4 which are thus arranged in a series-of horizontal rows and vertical columns, nine horizontal rows and seven vertical columns being provided in the specific example illustrated.

Each panel' i is provided with a masking means comprising a sheet 5' of rigid material extending between adjacent vertical cross-strips 3 and sliding in grooves 6 provided in these cross-strips. Each vertical column of panels 4 is provided with a single and common masking sheet 5 which extends fromthe top to bottom of the column and, in the case'of all but the extreme right-hand column, carries at its upper end a rack i (see Fig. 4), the purpose of which will be hereinafter explained.

Provided in the masking sheets 5 are a series of windows 8, one for each panel 4, and these windows may be constituted by simple apertures formed in the sheet, or by apertures in which is mounted a fiat or curved plate 'of glass or other transparent material. Windows '9 are also provided in the surface 2 of the casing adjacent the lower end of this surface.

' As will be observed from Figs. 1, 5 and 6 of the drawings, certain ofthe Windows '8 are double the width of the others and are provided with a slidable shutter Hi, this shutter comprising a substantially rectangular plate provided midway along its'length with an opening I I of an area corresponding to that of the windows 8 which are not provided with a shutter. The shutters Iii are slidably mounted in-channel-shapedguides I2 secured to the respective sheet 5, and are each provided with an operating knob I3'by means of which the shutter can be slid endwise so that the openings II therein can be made to register with either the left-handor the right-hand half of the enlarged window 8 therebeneath.

Mounted within the casing I are a plurality of rotatable elements in the form of rollers It, one being provided for each vertical sheet 5 and being arranged beneath the l'atter with the surface of the roller closely adjacent the underside of the sheet. The roller are of similar form and each has its axis parallel with the longitudinal centre line of its corresponding masking sheet 5;

Each roller has a main body portion I5 which extends from the lower edge of the lowermost panel to the upper edge of the uppermost panel of the corresponding vertical column of panels 4, and this body'portion may be of circular or polygonal (and preferably undecagonal) shape in section. At its bottom end each roller I4 has secured thereto a cylindrical spindle I6 of reduced diameter (see Figs. 3 and 4) this spindle I6 being mounted in a roller-supporting block 4 or partition I'I provided within the casing I. At its lower end the spindle I5 terminates in a further cylindrical or polygonal roller portion IB which co-operates with the windows 9 in the casing. Secured to the lower end of the roller portion I8 is a roller-actuating knob I9 which is located outside the casing 'I (see Fig. l).

The upper end of each of rollers I4 is also provided with a spindle 25, and these spindles 20 are mounted in a common bearing block or partition. 2I located within casing I and extending across the width of the latter. Each of the spindles 25, except that of the last left-hand roller, carries at its outer end a bevel pinion 22; this pinion being in mesh with a pinion 23 having a sleeve 24 integral therewith. The sleeve ZG'is-in turn connected to a further toothed wheel 25, the teeth of which engage with those of the rack' 1 provided on the sheet 5 corresponding to the next adjacent roller. The sleeves 24 are all loosely mounted on a common shaft 2-8 extending from one side to the other of the casing I-.

It will therefore be observed that when one of the rollers It is rotated, the gearing 22, 23, 25 and "I produces a longitudinal movement of the slidingsheet 50f the next column to the left. The amount of longitudinal sliding of thi sheet 5 is conjugated to the degree of rotation of the roller i4 concerned, by selecting the appropriate numbers of teeth on the pinionsZZ-and 23 and toothed Wheel 25, so that a predetermined amount of rotation of the roller produces longitudinal sliding of the sheet by the amount required to produce a predetermined movement of the windows 3 therein, for the purposes to be described hereafter.

Each of the rollers It is provided with nine sets of vertically-spaced. tables arranged around the perimeter of the body portion l5 by marking or printing the surface of: the latter or by winding a marked o printed web. of paper or other suitable material around this body portion I5.

In the case of the extreme right-hand roller, 1. e. that corresponding, to the units column, each table consists of a single horizontal. row of figures as illustrated in Figs. 7A and 7B of thedrawings, which represents the marked surface'of the righthand roller It initsdeveloped form. It will be noted that there are ten equally-spaced digits in each row and that successive rows are at different levels relatively to their particular section of the'roller, so as to register withthe' corresponding, fixedly-positioned windows v8 of the right-hand vertical. column of the device (see Fig. 2).

As seen in Fig. 7, the roller portion I8 also carries a horizontal row of key digits, viz., the numbers 1 to 0, these digits being in vertical alignment with the figures of the other horizontal rows of the roller and. being adapted to appear, in turn, at the extreme right-hand window of the row of windows 5 which-exhibit the key row digits 0 to 9 marked on the roller portion l8, and, in certain cases, ten subsiduary vertical columns each arranged at the right-hand side of one of the main vertical columns, these subsidiary vertical columns being designed to indicate the result of a two-denominational carry-over as will be explained hereafter.

It will also be noted that there is a blank vertical co1umn in each table corresponding to the neutral position of the roller, marked with a square on the roller portion [8.

Certain of the digits of the tables in Figs. 8A and 8B (and their counterparts in Fig. 2) have been shown ringed. This is to indicate that the figures concerned will be differently marked from the un-ringed digits, e. g. they may be coloured red as against the use of black for the un -ringed digits.

When one of these characteristically marked digits appears at a window, it is a signal to the user of the device to shift the shutter ID of the panel 4 of the next higher denomination (in the same horizontal row of panels) to the right so as to expose a digit in a subsidiary vertical column of the table and obscure the digit of the main vertical column originally shown.

Each of the multiplication tables shown in Figs. 8A and 8B contains in each of its ten horizontal rows of digits a series of ten main entries for each of the nine digital products 12, Zn, 3n 9n, where n is the corresponding digit in the key horizontal row. The ten vertical entries for each digital product consists of the units figures only of the numbers rn+Co, rn-i-Ci, rn+C2 rn+C9, where r is the digital multiplier and or is the units figure of the number which has to be carried over from the next lower denomination when the integer in that denomination of the multiplicand is k.

By the use of the carry-over gearing and the sliding masking sheets 5, described above, the arrangement is such that in any one adjusted position of a particular sheet 5, only those entries which correspond to one particular value of k (i. e. only those entries relating to a particular value of the figure in the next lower denomination of the multiplicand) are visible through the windows 8 therein. Each window thus has ten positions in its panel 4 corresponding to the ten possible values of is, plus an eleventh and bottom position corresponding to a neutral setting of the preceding roller.

As has already been indicated, when the quantity to be carried over is greater than nine, and therefore a part of this quantity has to be carried over to the next denomination but one, this fact is signalled by the appearance of a red or otherwise characteristically-marksd digit in the first carry-over column and the operator has merely to move the appropriate shutter in the next higher column to expose the entry in the corresponding subsidiary column. These subsidiary entries consist of integers each of which is greater than the integer of the main entry, with which it is associated, by the number (one) to be carried over from the second-lower denomination. It will be noted that the subsidiary entries, like the main entries, are uni-digital, and they may therefore include the whole of the quantity to be carried over from previous denominations or only the units digit of that quantity. Those subsidiary entries which include part only of the total quantity to be carried over are also marked in a distinguishing fashion so as to signal to the operator that, once again, the

6 shutter of the next higher denomination must be shifted.

It will be apparent that when the device is in use the knobs l9 can be operated so as to turn the corresponding rollers and exhibit a key digit at the corresponding window 9. Simultaneously appropriate digits will be shown at the various windows 8 of the device and the tables shown in Figs. 7A and 7B and Figs. 8A and 813 have been so calculated, in combination with the constructional features of the device which have been described, that when a factor is set up in the key column, as indicated through windows 9, the figures which appear at the windows 8 of the successive horizontal columns of panels 4 give the products of this factor and 1 to 9 respectively after, if necessary, operation of some of the shutters I0. It will be seen that these horizontal columns have been correspondingly marked lac 9:13 on the front surface 2 of the casing.

To illustrate the actual functioning of the device a specific example has been indicated in Fig. 2, viz. the series of partial products of the factor 739 which are set up in the apparatus when the knobs IQ of the three right hand rollers are appropriately operated to exhibit this factor in the key windows 9. It will, of course, be appreciated that no movement has been made of the knobs IQ of the four left hand rollers, but that such operation, required if a larger factor were to be multiplied, would follow the same pattern.

The procedure followed to produce the products of 739, and its results, are given in the following description, in which it will be assumed that we start with all the figures in the key windows 9 at zero. In this condition all the windows 8, except those of the fixed right-hand column, are located in their starting positions, i. e. at the bottom of the respective panel 4 as in the case of the three left-hand columns in the illustration of Fig. 2. I

The extreme right hand roller is first rotated until the figure 9 appears in the corresponding key window 9. This results in a series of figures 9, 8, 7, 6, and so on, i. e. the digits in the left hand column of Figures "1A and 7B, appearing in that order downwards in the right-hand column of the device. At the same time this rotation of the right hand roller causes, through the corresponding gearing 22-25 and rack I, the movement of the masking sheet 5 of the next adjacent column (the tens column) into its ninth position, that is the windows of this sheet move up in each case to the top of the associated panel 4.

Thus the figures exposed at this stage by the windows of the two right hand columns is DWNHO cncaqooco etc. 8 1

i. e. the successive products of 9 multiplied by 1 9.

The second roller from the right is next rotated until the digit 3 is exposed at the corresponding key window 9. The consequent rotation of the tables on this roller brings a new set of figures into the windows of the second column, and the simultaneous movement of the masking sheet 5 of the next left-hand adjacent column, i. e. the hundreds column. The resultant movement of the windows of this sheet into the third posiamavso 7 tion exposes a column of figures, so that the totals now become:

1 1 7 and so on,

i. e. the partial products of the factor 39 appearing in the key row.

Finally, the third roller is rotated to bring the figure 7 into the corresponding window 9, with the consequentselection of new figures in the third colmn and the conjugated movement of the masking sheet '5 of the fourth column to expose appropriate figures as indicated in Fig. 2. In this connection it is to be noted that certain of the figures exhibited are of the ringed or coloured type, wherefor appropriate adjustment is made of the shutter'of the next left-hand panel in the same row.

The result is that a series of partial products, representing the successive multiples 1 to 9 times 739, have been set up at the reading surface of the device.

Thus ,.any product from 1 to 9 times the multiplicand can be set up and read oil? the device. Multidenominational multipliers up to any num bers of digits can be dealt with by the method of successive multiplication by single digits and addition of the partial products. To this end, each partial product may be read from the device and written down with each successive partial product shifted one space to the left of the preceding partial product (as in a normal multiplication sum) and the final product obtained by addition of the partial products,

Alternatively, the partial products may be fed into an adding machine as they are read ofi the calculating device according to this invention.

Division is carried out by first setting up the divisor in the key column of the calculating device so that the horizontal columns of digits exhibited give all the products from 1 to 9 times the divisor. If the quotient is a single-digit number, one of these products will be axactly equal to the dividend and the quotient will, therefore, be immediately evident from inspection of the products exhibited. If, however, the quotient contains two or more digits, the first digit is determined by selecting from the products exhibited that which is nearest below the number denoted by the first 11. digits of the dividend, where n is the maximum number of digits in the divisor. The next digit of the quotient is obtained by selecting from the products exhibited that which is equal to or next below the first n digits of the remainder when the product previously selected is subtracted from the dividend.

Succeeding digits of the quotient are found in like manner and the quotient can thus be determined to any required number of significant figures by the method of successive division of remainders. 1

Although reference has been made throughout to a device in which the partial products are set up in a series of horizontal rows, with the corresponding figures of these rows arranged in vertical columns, it will be readily appreciated that an opposite arrangement is possible, i. e. {or the partial'produots to be arranged in vertical columns and the corresponding individual digits in horizontal alignment, and the words column and row used in the appended claims are to be readas including this modified arrangement.

i It will also be apparent that many changes can be made in the embodiment of the invention without departing from the spirit of the latter as set out inthe ensuing claims. Thus, for example,the sizeof the apparatus can vary within wide limits and theapparatus reduced, for instance, to a small compass enabling it to be easily carried around. In this event a magnifying cursor could be used in association with the exposed digits to enable them to be more easily read.

I claim:

1. A calculating device comprising a plurality of rotatable elements each having associated therewith a plurality of figures, apertured, longitudinally-movableslide means co-operating with each of said rotatable elements for exposing selected figures of said elements through said apertures, and means for automatically transmitting the movement of certain of said rotatable elements to the slide means associated with the next adjacent rotatable element for selecting an appropriate figure from this element for exposure.

2. A calculating device comprising a plurality of rotatable elements each having associated therewith a plurality of figures, longitudinallymovable slide means cooperating with the rotatable elements representing all but the lowest denomination and having apertures therein for exposing selected figures of these rotatable elements, and means for automatically transmitting themovement of each of the rotatable elements, except that representing the highest denomination, to the .slide means associated with the rotatable elementlof the next-higher denomination.

3. A calculating device comprising a plurality of rotatable elements located side by side with their axes of rotation. parallel, said elements each having associated therewith a plurality of figures, a framedividing upthe indicating surface of said device into a plurality of panel areas arranged in rows and columns, slide means co-operating with the rotatable elements representing all but the lowest denomination and movable in the direction of the axes of rotation of said rotatable elements, said slide means :having apertures therein for exposing selected figures of these rotatable elements-and anaindividual'slide means being associated with each column of panel areas except that representing the lowest denomination, and means for automatically transmitting the movement of each of therotatable elements, except that representing the highest denomination, to the slide means associated with the rotatable element of the next-higher denomination.

4. A calculating device comprising a plurality of rotatable elements,'pre-calculated tables of figures associated with each of said rotatable elements and movable in response to rotation of the associated rotatable element to bring a predetermined set of figures into exhibiting position, apertured slide means co-operating with each of said rotatable elements for exposing selected figures of said sets through the apertures in said slide means, and means for automatically transmitting the movement of certain of said rotatable elements to the slide means associated with the next adjacent-rotatable element for selecting an appropriatefigure for exposure from the table associated with this element.

5. A calculatingdevice for performing-multiplication comprising a plurality of rotatable elements, pre-calculated tables of figures associated with each of said rotatable elements and movable in response to rotation of the associated rotatable element to bring a predetermined set of figures into exhibiting position, said tables including subsidiary entries representing digits obtained by a two-dimensional carry-over and including characteristically-marked digits representing the residual first-higher-denominational figure of a two-denominational carry-over, apertured slide means co-operating with each of said rotatable elements for exposing selected figures of said sets through the apertures in said slide means, and means for automatically transmitting the movement of certain of said rotatable elements to the slide means associated with the next adjacent rotatable element for selecting an appropriate figure'for exposure from the table associated with this element. i

6 A calculating device for performing multiplication comprising a plurality of rotatable elements, pie-calculated tables of figures associated with each of said rotatable elements and movable in response to rotation of the associated rotatable element to bring a predetermined set of figures into exhibiting position, said tables including subsidiary entries representing digits obtained by a two-dimensional carry-over, means for signalling the need for selecting digits from said subsidiary entries to conform with such carry-over, apertured slide means co-operating with each of said rotatable elements for exposing selected figures of said sets through the apertures in said slide means, means for automatically transmitting the movement of certain of said rotatable elements to the slide means associated with the next adjacent rotatable element for selecting an appropriate figure for exposure from the table associated with this element, and shutter means manipulatable in accordance with the indications of said signalling means, for selecting a digit from the subsidiary entries for exposure.

'7. A calculating device for performing multiplication comprising a plurality of rotatable elements, pre-calculated tables of figures associated with each of said rotatable elements and movable in response to rotation of the associated rotatable element to bring a predetermined set of figures into exhibiting position, each of said tables, except that associated with the first rotatable element, comprising ten vertically-spaced rows of horizontal figures representing the digits of the products 1 to 9 times the value of the table plus an appropriate carry-over (if any) from the next lower denomination, apertured slide means cooperating with each of said rotatable elements for exposing selected figures of said sets through the apertures in said slide means, and means for automatically transmitting the movement of certain of said rotatable elements to the slide means associated with the next adjacent rotatable element for selecting an appropriate figure for exposure from the table associated with this element.

8. A calculating device comprising a casing having an indicating surface, a plurality of rollers located within said casing and below said indicating surface, lore-calculated tables of figures carried by each of said rollers, apertured slide means aligned with each of. said rollers and movable parallel to the axis of the associated roller for exposing selected figures of the latter through said apertures, and means for automatically transmitting the movement of each of the rollers, except that representing the highest denomination, to the slide means associated With the roller of the next-higher denomination.

9. A calculating device comprising a plurality of rotatable elements each having associated therewith a plurality of figures, pre-calculated tables of figures carried by each of said rotatable elements, a set of key figures also carried by said rotatable elements, means co-operating with each of said rotatable elements for exposing selected figures of said elements, means co-operating with said key figures for exhibiting a key figure selected from said set by rotation of the corresponding rotatable element, and means for automatically transmitting the movement of certain 'of said rotatable elements to the figure-exposing means associated with the next adjacent rotatable element for selecting an appropriate figure from this element for exposure.

10. A calculating device comprising a plurality of rotatable elements each having associated therewith a plurality of figures, longitudinallyslidable means co-operating with each of said rotatable elements for exposing selected figures of said elements, and toothed gearing for automatically transmitting the movement of all except the last of said rotatable elements to the figure exposing means associated with the next'adjacent rotatable element for selecting an appropriate figure from this element for exposure.

11. A calculating device comprising a plurality of rotatable elements each having a set of figures associated therewith, means for exposing selected figures from said sets with these figures arranged in columns, and in rows which represent successive products of an arbitrary factor, each said figure-exposing means being associated with a rotatable element, and means responsive to the movement of each rotatable element to impart correlated movement to the figure-exposing means of the next adjacent rotatable element, whereby each figure (except those of the first column) is exposed in joint dependence on the setting of the rotatable element with which it is associated and the setting of the next-preceding rotatable element.

12. A calculating device comprising a plurality of rotatable elements each having associated therewith a plurality of figures, movable means normally masking figures of said rotatable elements, said movable means being apertured to expose to view from said plurality of figures columns of selected figures arranged in rows representing successive products of an arbitrary factor, and slide means for controlling the position of each said movable means in dependence on the rotary setting of the rotatable element in the next-preceding column.

13. A calculating device comprising a plurality of rotatable elements, pre-calculated tables of figures carried by each of said rotatable elements, movable means for exposing selected figures from said tables with these figures arranged in columns, and in rows which represent successive products of an arbitrary factor, each said figureexposing means being associated with a rotatable element, and gearing means transmitting the movement of each rotatable element to the figureexposing means of the next adjacent rotatable element, whereby each figure (except those of the first column) is exposed in joint dependence on the setting of the rotatable element with which it is associated and the setting of the next-preceding rotatable element.

14. A calculating device comprising a plurality of rotatable elements, pre-calculated tables of figures carried by each of said rotatable elements, certain of said tables including columns of figures representing the resultant of the addition of a digit carried over from the previous denomination but one, movable means normally masking figures of said rotatable elements. said movable means being apertured to expose to view from said plurality of figures columns of selected figures arranged in rows representing successive products of an arbitrary factor, shutter means on said movablemeans and associated with certain ofthe apertures of said movable means for exposing a figure. to view through a part only of the corresponding aperture, means for controlling the selective exposure, of figures in joint dependence on the setting of the rotatable element carrying this figure and the setting of the next-preceding rotatable element, and means associated with said tables for signalling appropriate operation of respective shutter means.

15. A calculating device comprising a casing havingan indicating surface, a plurality of rollers located within said casing and below said indicating surface, pre-calculated tables of figures carried by each of said rollers, movable means normally masking figures of said rollers, said movable means being apertured to expose to view from said plurality of figures columns of selected figures arranged in rows representing successive products of an arbitrary factor, toothed gearing transmitting the movement of each roller to the movable masking means of the next successive roller for, varying the portion of the tables of this roller exposed through the apertures in said movable masking means, and a row of key figures carried by each roller and co-operating with an aperture in said indicating surface for identifying the rotational setting of the associated roller.

LOUIS MILES NATION-TELLERY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

